1. Technical Field
One or more embodiments of the present invention generally relate to a system and method for evaluating an integrated coil on plug ignition system for an internal combustion engine.
2. Background Art
An ignition system for an internal combustion engine is an electrical system that provides a spark for igniting fuel within the engine to initiate combustion. The ignition system typically comprises an ignition coil coupled to both a electrical switch and a spark plug. The spark is triggered by an interruption of current flow within the ignition system which creates a high voltage signal that arcs across a spark plug to create a spark. There is a trend within automotive industry to mount the ignition coil directly to the corresponding spark plug. Such a system may be referred to as a coil-on-plug (CoP) ignition system. Additional trends within the automotive industry include integrating each electrical switch into a housing of the corresponding CoP assembly. Such a system may be referred to as an integrated CoP ignition system.
The ignition system is typically assembled to the engine at an engine assembly plant. An End of Line (EOL) tester may be used to evaluate the performance of the engine and its associated systems. Conventional EOL testers evaluate the ignition system by measuring an electrical signal present on an ignition circuit between the ignition coil and the electrical switch. A flyback voltage signature is present on the electrical signal when the ignition coil is fired. The flyback voltage is measured and compared to pre-existing data to evaluate the ignition system. Such an ignition system generally provides an external point that is accessible to a user to monitor the electrical signal.
However, by integrating the switch within the housing of the ignition coil, it may not be possible to gain access to any point between the ignition coil and the electrical switch. As such, the flyback voltage is not capable of being ascertained.
One conventional strategy for evaluating the performance of an integrated CoP ignition system includes obtaining the flyback voltage via an RF based system for example. An RF based antenna may detect an electrically radiated inductive noise spike that is generated when the ignition coil is fired. Such an approach requires an array of antennas and additional sensors that are sensitive to the placement and pickup of other uncontrolled stray electrical noise.